VARIATION OF THE PORE STRUCTURE DURING MICROWAVE PYROLYSIS OF OIL SHALE

Thermal maturity has a considerable impact on hydrocarbon generation, mineral conversion, nanopore structure, and adsorption capacity evolution of shale, but that impact on organic-rich marine shales containing type II kerogen has been rarely subjected to explicit and quantitative characterization. This study aims to obtain information regarding the effects of thermal maturation on organic matter, mineral content, pore structure, and adsorption capacity evolution of marine shale. Mesoproterozoic Xiamaling immaturity marine oil shale with type II kerogen in Zhangjiakou of Hebei, China, was chosen for anhydrous pyrolysis to simulate the maturation process. With increasing simulation temperature, hydrocarbon generation and mineral transformation promote the formation, development, and evolution of pores in the shale. The original and simulated samples consist of closed microspores and one-end closed pores of the slit throat, all-opened wedge-shaped capillaries, and fractured or lamellar pores, which are related to the plate particles of clay. The increase in maturity can promote the formation and development of pores in the shale. Heating can also promote the accumulation, formation, and development of pores, leading to a large pore volume and surface area. The temperature increase can promote the development of pore volume and surface area of 1–10 and 40-nm diameter pores. The formation and development of pore volume and surface area of 1–10 nm diameter pores are more substantial than that of 40-nm diameter pores. The pore structure evolution of the sample can be divided into pore adjustment (T < 350°C, EqRo < 0.86%), development (350°C < T < 650°C, 0.86% < EqRo < 3.28%), and conversion or destruction stages (T > 650°C, EqRo > 3.28%). Along with the increase in maturity, the methane adsorption content decreases in the initial simulation stage, increases in the middle simulation stage, and reaches the maximum value at 650°C, after which it gradually decreases. A general evolution model is proposed by combining the nanopore structure and the adsorption capacity evolution characteristics of the oil shale.

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The Pyrolysis Characteristics and Pore Structure of Oil Shale of Different Densities

Energy Procedia ◽

10.1016/j.egypro.2012.02.182 ◽

2012 ◽

Vol 17 ◽

pp. 876-883 ◽

Cited By ~ 7

Author(s):

Qing Wang ◽

Ling-Wen Kong ◽

Jing-Ru Bai ◽

Zeng-Ying Gu

Keyword(s):

Pore Structure ◽

Oil Shale ◽

Pyrolysis Characteristics

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Pore Structure Petrophysical Characterization of the Upper Cretaceous Oil Shale from the Songliao Basin (NE China) Using Low-Field NMR

Journal of Spectroscopy ◽

10.1155/2020/9067684 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Xin Liu ◽

Jinyou Zhang ◽

Yunfeng Bai ◽

Yupeng Zhang ◽

Ying Zhao ◽

...

Keyword(s):

Pore Structure ◽

Oil Shale ◽

Upper Cretaceous ◽

Distribution Patterns ◽

Songliao Basin ◽

Shale Oil ◽

Low Field ◽

Wide Range ◽

Low Field Nmr

Low-field NMR theory was employed to study the pore structure of the upper cretaceous oil shale, on the basis of fourteen core samples collected from Qingshankou (UCQ) and Nenjiang (UCN) formations in the Songliao basin. Results indicated that the T2 spectra from NMR measurements for collected samples contain a dominant peak at T2 = 1∼10 ms and are able to be categorized as three types—unimodal, bimodal, and trimodal distributions. The various morphologies of T2 spectra indicate the different pore type and variable connection relationship among pores in shale. By contrast, UCN shale has more single pore type and adsorption pores than UCQ shale. Besides, NMR-based measurements provide reliable characterization on shale porosity, which is verified by the gravimetric approach. Porosities in both UCN and UCQ shales have a wide range (2.3%∼12.5%) and suggest the strong heterogeneity, which partly makes the challenge in selection of the favorable area for shale oil exploration in the Songliao basin. In addition, the pore size of the collected sample has two distribution types, namely, peaked at ∼10 nm and peaked at ∼100 nm. Similarly, two distribution patterns emerge to the specific surface area of the study shale—peaked at ∼2 nm−1 and peaked at ∼20 nm−1. Here, more investigations are needed to clarify this polarization phenomenon. Basically, this study not only exhibits a preliminary understanding on the pore structure of the upper cretaceous oil shale, but also shows the reliability and pertinency of the low-field NMR technique in the petrophysical characterization of the shale oil reservoir. It is expected that this work is helpful to guide the investigation on the pore structure of oil shale from the Songliao basin in theory.

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Study on Porous Structure and Fractal Characteristics of Oil Shale and Semicoke

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.868.276 ◽

2013 ◽

Vol 868 ◽

pp. 276-281

Author(s):

Li Mei Zhao ◽

Jie Liang ◽

Lu Xin Qian

Keyword(s):

Porous Structure ◽

Pore Structure ◽

Oil Shale ◽

Fractal Dimensions ◽

Isothermal Adsorption ◽

The Matrix ◽

Fractal Characteristics ◽

Adsorption Desorption ◽

Desorption Method ◽

Skeleton Structure

In order to find the change rule of porous structure of oil shale during pyrolysis, the Huadian oil shale samples were heated to final temperature of 300°C400°C500°C600°C700°C. The pore structure and pore size distribution of oil shale and produced semi-cokes were measured by N2 isothermal adsorption/desorption method. The fractal characteristics and other parameters of porous structures were then analyzed in detail. The results indicate that the pores in oil shale were open at one direction while the pores in semi-cokes could be observed from two or even four directions. The pore sizes of semi-cokes were mostly between 3-5 nm; and the pore volume increased at a quickest rate when pyrolysis temperature increased from 400 to 600 °C. Oil shale and its semi-cokes all showed obvious fractal characteristics, whereas oil shale and the semi-coke from 600 °C gave the lowest fractal dimensions; this means that the matrix of oil shale tended to keep its original skeleton structure and the pore structure of semi-cokes from high temperatures became regular after devolatilization during the pyrolysis.

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